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by klelatti 1337 days ago
The author seems to have been quite wound up by claims that "my high end desktop / server (insert ARM / RISC-V to taste) is better than your x86 because 'RISC'".

Fair enough. It's an 80's debate really. ISA is probably by a long margin not the most important factor in these comparisons.

But he says it makes no difference at all without evidence.

And he ignores that there is a whole world of simpler (especially in-order) cores where ISA probably does matter a lot.
1 comments
noobermin 1337 days ago
In the case it was missed, he actually does talk about that towards the end, that it matters for low powered microcontrollers and for people unwilling to pay for an ARM license, but for the higher powered machines (ARM machines, x86_64 etc), they are both OoO and that is more of what makes them powerful for modern computing ("real" computing by his definition) than does the RISC vs VAX lineage matters.
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klelatti 1337 days ago
He talks about it for microcontrollers but conveniently ignores a whole range of CPUs between this class and OoO because they don't fit his argument. eg from Wiki:

> The Cortex-A53 is the most widely used architecture for mobile SoCs since 2014 to the present day, making it one of the longest-running ARM processors for mobile devices. It is currently featured in most entry-level and lower mid-range SoCs, while higher-end SoCs used the newer ARM Cortex-A55. The latest SoCs still using the Cortex-A53 are MediaTek Helio G37, both of which are entry-level SoCs designed for budget smartphones.

These may not be the most exciting CPUs but does the ISA matter here? Yes probably quite a bit. Does it matter that they are compatible with beefier OoO cores in say a big.LITTLE configuration. Yes it does.

I wouldn't mind too much if he had said I'm just talking about high end. But he implicitly claims to cover everything except 100k transistor CPUs.

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zozbot234 1336 days ago
ISA is a very real constraint on the width of insn decode for something like x86-64, when compared to AArch64 and even more clearly, to RV64C (which competes in code density with x86-64).
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